Re-entrant window for X-ray apparatus



March 21, 1944. J, H. FINDLAY 2,344,543

REENTRANT WINDOW FOR X-RAY APPARATUS Filed Jan. 31, 1942 INVENTOR -I H.F'WVDZfi) ATTORNEY Patented Mar. 21, 1944 RE-ENTRAN T WINDOW FOR X-RAYAPPARATUS John FindlamUpper Montclair, N. J., assignor to WcStInghouseElecti-ic & Manufacturing Company, East Pittsburgh, Pa., a corporationof Pennsylvania Application January 31, 1942, Serial No. 429,046

'1 g g p 5 Claims.

This invention relates to shockproof X-ray units, especially to thoseoperable for prolonged periods of time, as in the administration oftherapeutical treatment for diseases and in industrial radiography, andrelates more particularly to the type of X-ray unit in which the X-raytube is enclosed with an X-ray-opaque metal casing and is immersed in abody of cooling and insulating fiuid, such as oil, confined by thecasing, the latter having an X-ray-pervious window which defines thepath of emission of the X-rays, directed through the window by the anodein known fashion.

X-ray units of this general construction are in successful commercialoperation, and an example is shown in Simon Patent 2,049,275, issued tothe owner of the instant application. Such units, heretofore, have beensubject to the disadvantage in operation that a filmi of the oil hasexisted in the space between the window of the casing and the nearestpoint on the periphery of the X-ray tube, the film extending across thepath of the X-rays and affecting unfavorably the efiiciency of the beam,especially in the important respect that the oil exerts a filtering andscattering effect which thus affects the quality of the X-rays actuallyavailable for use.

It has been proposed by prior workers in the art to reduce the film ofoil between the X-ray tube and the surrounding casing to a minimum bythe provision of an oriented window; but where X-rays of long wavelengthare desired, even a very thin film of oil greatly affects the quality ofthe X-rays, as does the composition of the casing window, due to theirresulting filtering action.

It is accordingly an object of the present invention to eliminatethedisadvantages and inconveniences'of operation due to the film of oiland easing window by providingmeans to exclude the oil completely fromthe path of the X-rays, so that no film or intervening filter exists atthat region.

Another object is to provide the X-ray tube with a hollow bossconstituting a permanent part of the structure of the tube, surroundingand aidtubes so constructed may be substituted'for a defective X-raytube in the same casing. Still further objects of my invention willbecome apparent to those skilled in the art by reference to theaccompanying drawing wherein:

Figure 1 is an elevational view of a shockproof X-ray unit constructedin accordance with my present invention, parts being broken away toreveal inner structure;

Fig. 2 is a fragmentary sectional view-taken on the line IIII of Fig. l.

Fig. 3 is a similar vertical cross-sectional section of a modificationwhich the present invention may take, and

Fig. 4 is an elevational view of the X-ray tube of Fig. 1, taken as anentity separately from the casing. 1

Referring now to the drawing in detail, I have shown in Fig. 1 ashockproof X-ray unit, com-v prising an X-ray tube designated generallyby the reference character 6, and illustrated separately as a completeentity in Fig. 4, the unit as shown including also a shockproof metalcasing designated generally by the reference character 1, the same beingpreferably of approved structure constructed and arranged to support theX-ray tube 6 of Fig. 4, in a position extending substantially axially ofthe casing 1, wherein it is immersed in a body 8 of cooling andinsulating fluid, such as oil, according to-known or other--- wisesuitable practice.

The casing as shown in Fig. 1 is madeup of a middle section 9, providedat- H) with a window for passage of the X-rays directed therethrough bythe anode ll of the X-ray tube, which, with the cooperating cathode [2,are suitably disposed to produce that effect, and the casing furtherincludes end sections l3 and I4 and intermediate sections l5 and I8,which are combined in the completed structure to support the X-ray tubein its proper position, together with'its asso ciated parts, includingleading-in conductors and terminals, all of which may be, and preferablyare, of substantially conventional structure,- known to those skilled inthe art and which do not require further description.

In pursuance of the invention I provide means for completely excludingthe oil from the path of the X-rays, and in the present embodiment ofthe invention as illustrated in the accompanying drawing, thisoil-excluding means comprises as its main element a hollow boss I1,preferably formed integral with the walls of the X-ray tube and of thesame vitreous material as manner,

and surrounding an area of reduced cross section in the envelope wall ascan be readily seen in the several figures.

The boss I! is so disposed that it may be brought readily into alignmentwith the axis of the window Ill of the casing, and thus forms a windowing the envelope wall which aids in defining the path of the-X-raystherethrough. The next element in order of the oil-excluding means,comprises a bushing [8 made of Kovar metal or of some like metal havingthe property of ready physical connection with glass and also havingsubstantially the same coefficient of expansion under the heatencountered in the operation of the X-ray unit. The end H) of the Kovarbushing is attached directlyto the glass boss 11, of which it isdesigned to form a permanent part, and the invention providesfortheaddition to the metal bushing of a bracket 20 which is preferablysecured permanentl to the bushing l8, as by a metallic unionsuchaswelding, so that. it is integrated therewith and constitutes aunitary structure with th X-ray tube and may be stored, transported andinstalled as such.

The bracketlll has a slightly arcuate contour conforming. to that of theinterior wall of the casing at the region thereof; 2| surrounding thewindow [0, and Various means may be provided to efiectits attachment tothe casing. I

For example, in the structure of Fig. 1, the bracket 20 is shown assecured by screws 22 engaging tapped holes 23 in the bracket and ex-.tending through the wall of the casing. When so disposed,.the screws maybe used also to effect attachment of a flangeof annular cross section tothe casing which is engaged by a conventional X-ray directional cone 39,the latter being designated generally by the reference character 24- andwell-known in the art.

One branch 26' of this flange Of annular cross section is threaded toreceive. a threaded end 21 of the cone 24, while the other branch 29 ofthe flange is pierced to permit the passage of the screws 22- which,engage the tapped holes 23 in the bracket 2|],as before mentioned. V

In the. modification as shown in Fig. 3, the

lower end of the Kovar bushing I8 is threaded exteriorly, as at 32, toreceive a threaded. retaining ring 34, which is run up on the end32,.plac-' ing under compression a packing ring orgasket 33, against theexterior wall 35 of the casing.

If desired, the wall 35 may be provided with a hollow boss 36 having aninteriorly threaded mouth 31 into which may be screwed a correspondinglythreaded flange 38 on the direction cone 39 in a manner similar to theother modification. 7 1 y Itis to be. noted that packing rings orgaskets 33 may be provided wherever they may be required, as shown inthe several embodiments of the present invention. I

When the parts above describedv are assembled,. it is readily seen thatthey completely enclose and define'the path of the X-rays and excludetherefrom any 011 com the body 8 thereof, the X-rays having only topenetrate the glass envelope. of the tube which can be'made thin at thewindow, thus carrying into effect the primary object of the invention asset forth in the opening'para'graphs of this specification;

Although several embodiments of the present invention have been shownand described, it is to be understood that" still further modificationsof the same can be made without departing from the spirit and scope ofthe appended claims.

I claim:

1. A shockproof X-ray unit comprising a metallic X-ray-opaque metalcasing provided with an X-ray-pervious window, an X-ray tube en closedwithin said casing and provided with a cathode and an anode whichbecomes heated during operation, said anode being arranged to emitX-rays in a path extending laterally through the walls of saidtube anddefined by said window, abody of" cooling and insulating fluid in saidcasing and immersing said X-ra tube, and means-hermetically sealed tosaid envelope and secured fluid-tight to said casing to exclude saidfluid from said path of X-ray emission.

2. A shockproof X-ray unit comprising a metallic X-rjay-opaque; metalcasing provided with an X-ray-pervious window; an X-ray tube enclosedwithin said casing and provided with a cathode and ananode" whichbecomes heated during operation, saidjanode beingi arranged to emitX-raysin a path extending laterally through the walls ofsaid tube. anddefined by said window, a I

body of cooling and insulating fluid insaid casing and immersing saidX-ray tube, and means to excludesaid fiuidirom said path of X-rayemission, said means including a. structure comprising an annularelement extending between and hermetically sealed to said tube andsecured i ght in s W nd 3. A shockproor X-ray unitcomprisinga metallicX-ray-opaque metal casing provided with an;X-ray-pervious window, anX-ray tube enclosed within said casing and' provided with a cathode andan anode which becomes heatedduring operation, said anode beingarrangedto emit X rays in a path extending laterally through the wallsof said tube and defined by said window, a body of cooling andinsulating fluid in said casing and immersing said X-ray tube, means toexclude said fluid from said'path of X-ray emissi'on,.said' meansincludingv a structure comprising an annular glass base formedas anintegral part ofthe envelope of sai'd'tube, and a metal bushingofannular'form hermetically sealedto said glass base and extending tosaid Window and serving to provide a fluid-excluding, area between theenvelope. ofsaid tube and said casing fl. Ashockproof X-ray unitcomprising. a metallic X-ray-opaqudmetal casing provided with an X-ray-pervious window, an X-ray tube enclosed within said casing andprovided with a cathodeand an anode which becomes heated duringoperation, said anodebeing arranged to emit- X-rays in a path extendinglaterally through the Walls of aid tube and defined by said window, abody of cooling and insulating fluid in said casing and immersing saidX-ray tube, means to exclude said fluid from said path of X-rayemission, said means including a structure compris ing an annular glassbase extendingfrom the:

envelope ofsaid tube and formed asan integral part thereof, a metalbushing of annular form hermetically sealedto said glass baseand'serving to extend the fluid-excluding area thereof,

and a flange forming part of said bushing and.

having fastening devices whereby it may be removably secured fiuidftighttosaid'ca'sing around said window. v

5. A shockproof 'X'-ray unit comprising a metallic X-ray-opaque metalcasing rovld'ed'with an X-ray-pervi'ous window; an X-ray tube" enclosedwithin said casingand' provided with a cathode and an anode whichbecomes heated dur+ ing operation, said anode being arranged to emitX-rays in a path extending laterally through the walls of said tube anddefined by said window, a body of cooling and insulating fluid in saidcasing and immersing said X-ray tube, and means to exclude said fluidfrom said path of X-ray emission, said means including a compositeannular structure hermetically sealed to said tube by an integral glassbase, and comprising a, metal annular part adapted to be removablysecured fluid-tight to said casing around said window by a mechanicalunion, said composite structure cooperating to exclude said fluid fromsaid path.

JOHN H. FINDLAY.

